At present, experiments and treatments using cells are diversified and performed in a variety of institutions and organizations for a variety of purposes. For example, these experiments and treatments include (1) basic studies primarily using animal cells and performed in university, state, and private research institutions, (2) basic studies using human cells and performed in medical college hospitals, state medical institutions, and pharmaceutical companies, (3) cell preparation for treatment purposes performed in medical college hospitals, pharmaceutical companies, and cell processing centers (CPCs) for medical treatment for which the patient bears the expense, (4) in microorganism operation, basic studies on pathogenic microorganisms that infect humans in university infection research laboratories and state infection research institutes, and (5) sterility tests performed in private food manufacturer examination section, agricultural laboratories, and hygienic laboratories.
Any of the studies using cells essentially requires experiments in a sterile or clean space. Since cells are very sensitive to infection and contamination, devices that handle cells are required to be extremely clean. It is, however, difficult to keep the device from contamination in everyday use, and it is therefore important to frequently clean and sterilize the device. Cleaning and sterilization of the device, however, have primarily involved rubbing-alcohol-based manual wiping and have not changed for about 30 years.
The rubbing-alcohol-based manual wiping can be readily performed, but a large burden is placed on operators and possible secondary contamination occurs during operation. Further, since the performance of the operation greatly depends on the skill of an individual operator, part of a device may unintentionally not be wiped, and the degree of achieved decontamination cannot be measured. Moreover, some fungi are not killed with rubbing alcohol, and persistently using the same chemical produces resistant bacterium. Spore-forming bacteria are not killed with rubbing alcohol either.
Some CO2 incubators have a built-in decontamination function, but such devices are used for dedicated purposes and hence cannot be used with other device having no decontamination capability. Further, a device having a built-in decontamination function performs sterilization at about 120 degrees by using dry heat sterilization typically in a sterilization period of about two hours and hence requires about ten hours for heat dissipation, resulting in inefficient sterilization. Moreover, since the device becomes very hot during sterilization, the heat affects a CO2 incubator located close to the device, which undesirably means that the nearby incubator cannot be used during the sterilization.
On the other hand, there is a known method in which a dedicated ultrasonic atomizer is placed in a CO2 incubator and hydrogen peroxide vapor is produced for decontamination (Patent Reference 1). In this method, however, the interior of the incubator is considerably wet, which requires a wiping operation, possibly causing secondary contamination.
Further, a UV bactericidal lamp is used to decontaminate a clean bench and other safety cabinets. In this method, however, only an area directly irradiated with the UV light is sterilized. Further, when the UV light is reflected off walls or other surfaces, the sterilization effect is undesirably greatly reduced. Moreover, under the current circumstances, rubbing-alcohol-based manual wiping is performed on an area that is not irradiated with the UV light.
Further, in operation and experimentation using cell incubation and microorganisms, a centrifugal separator is frequently used, and a centrifugal separation step is a step having a high risk of generation of aerosol.
This is because a sprayed substance produced at the time of operation in a safety cabinet is likely to adhere to a centrifugal separating tube and centrifugal operation very strongly agitates the sprayed substance in the air in a centrifugal chamber.
Further, when an angle rotor is used, in particular, aerosol is generated in a gap between the centrifugal separating tube and a cap produced by a difference in distortion due to a centrifugal force.
The thus generated aerosol is known to have a high risk that causes cell contamination and operator infection.
However, decontamination of the interior of the chamber of a centrifugal separator has not been performed because there has been no acceptable decontamination method.
As described above, there has been no device that efficiently decontaminates the interior of a device used with cell incubation, such as a CO2 incubator, a safety cabinet, and a centrifugal separator, without causing secondary contamination.
In studies in which infectious microorganisms are handled, the microorganisms are handled in a room designed to contain them for safety (P-3 room, P-4 room, and other biohazard rooms). In a safety cabinet in which unleashed microorganisms are handled, the microorganisms are likely to float therein or adhere thereto, but under the current circumstances, the cabinet is irradiated with UV light or rubbing-alcohol-based manual wiping is performed.
Further, to freeze and store the microorganisms, it is necessary to put them in a storage tube and take the storage tube out of the hazard room. In this process, an operator opens a door of the hazard room and places the tube in which the microorganisms have been placed in a pass box disposed in a space between the hazard room and a general area. The operator then opens a door of the general area and takes the tube out. In this process, it is typical that the tube is sealed and the outer surface thereof is cleaned with rubbing alcohol, but in the current state no checks are performed to determine that microorganisms are adhering to the outer surface of the tube in an exact sense.
As described above, there has been no device that prevents infection after aseptic operation and microorganism handling, specifically, that decontaminates not only the safety cabinet but also the biohazard room air in the pass box and the surface of the tube to be taken out.
Formalin gas fumigation is used for decontamination of the interior of a safety cabinet in some cases. Since formalin has, however, already been designated as a carcinogenic substance and is known to generate formic acid, paraformaldehyde, metaformaldehyde, and other highly corrosive, toxic residuals, formalin gas is hardly used under the current circumstances.
In food manufacturers and other places where sterility tests are frequently performed, microorganisms that adhere to food are inspected. To this end, culture-media-based incubation tests are typically performed. However, when a clean bench in which microorganisms are handled or a temperature controlled bath in which the incubation tests are performed is contaminated with fungi, accurate evaluation cannot be made. To avoid such a situation, rubbing-alcohol-based manual wiping is performed under the current circumstances.
As described above, there has been no device that readily decontaminates the interior of an inspection device from a quality control perspective either.